Process of recovering tin from waste.



ALBERT NODON, OF BORDEAUX, FRANCE.

PROCESS OF RECOVERING TIN FROM WASTE.

Specification of Letters Patent.

N Drawing.

To all "(1)7! om. a may concmai:

Be it known that l, Aiannrr NUUUN, of 12 tuc dc Moulis, Bordeaux, (lirouilc. France,

have invented certain new and useful lin- 5 provcn'ients in and Relating to Processes of Recovering Tin from aste, of which the following 1s a specification.

This invention has for itsobject to provide an improved process for the recovery of tin from all kinds of tin lead waste. and more particularly from waste tinned plate, Waste lead tin alloy and plated goods resulting from the manufacture of metal tin capsules, tin foil and tin tubes 1 The improved process consists in dissolv ing the tin alloyed with or adhering to the lead by subjecting the metal waste to the action of a. hot solution of stannie sulfate with the addition of sulfuric acid, mixed with an alkaline stannic haloid salt, which solution has no chemical action on lead, and then separating the tin from the solution by electrolytic means on tin electrodes in suitable galvanoplastic tanks.

The improved process is carried out as follows: At the beginning of the operations, the metal waste is cleaned in a dilute solu tion of sodium carbonate heated, and washed, for example, by means of a spraying rose. After the washing operation, the metal waste is submitted to the action of a solution of a stannic salt, more particularly an ammoniacal bichlorid of tin and stannic sulfa e con ainin an excess of free sulfuric acid. This stannlc liquor is maintained ata temperature of about degrees 0. Owing to the resence of the stannic sulfate and the sulfuric acid, the lead i n the metal waste is not acted on by the haloid salt, and only the 40 tiwisdissolvedifi the form of ammoniacal chlorid of tin. The same reaction is produced when the tin instead of being mixed with the lead, is alloyed with the latter. The lead freed from the tin which remains as the residue of the operation may be afterward melted down for reuse in manufacture. The stannic liquor resulting from the dissolution of the tin, is then conveyed into electrolytic tanks of which any desired number may be provided. T ese tanks are rnade oflsand vst or&%r any at erin it'fial'that is unaifct-d by :01 s. They contain gra hite anodes arranged against the inner si es of the tanks on either side of the cathodes. The cat odes are composed of pure tin, preferabl of 'lutentcll Nov. 1.6, 1909.

Application filed April 9, 1908. Serial No. 426,019.

sheets of tin contained in baskets or porous vessels of canvas placed in the center of the. tanks. These vessels retain the arborescent deposits of tin which are formed on the sides of the cathodes. The deposition is effected by means of an clectro motive force of 2 to 3 volts and a current strength of about 1 to 2 ainpcres per square deciineter of active cathode surface. The electrolytic tanks may be, for instance, 4 to (3 in number, coupled in series and fed by an eleetrolyzin dynamo, having an electromotive force 0. 15 to 20 volts according to the number of tanks coupled in series, and a current strength of from 100 to 300 amperes, according to the magnitude of the operations.

The strength of coi'icentration of the stannic liquor is kept constant during the entire process by checking its density by means of a densimeter or of a salt-scale.

lvllelrsufiicient tin has been deposited, it is washed overstrainers or canvas filters, in order to collect "the arborescent de osits of tin, the washing liquor being col ected at the bottom of the tank. The deposit is then melted down with the cathodes in order to utilize the metal again in manufacture.

The residual liquors collected are evaporated and when they have reached. the desired degree of concentration, they are returnd to the electrolytic tanks. The liquor which has been deprlved more or less of its tin by the electrolytic process, is returned into the solution tank. Thus the same liquor can be used over again for an indefinite period.

The improved process has the advantage of recovering the tin from lead as this latter metal is not affected by the solution. It is very economical because the chemical reaction and the electrolytic rocess constitute a. closed cycle in which the iquor is being constantly regenerated.

The improved process can be carried out with great regularit and it requires only a few hours it also yields pure lead that can be readily used again.

The improved process is applicable to the recovery of tin from its state of mixture or alloy with lead in waste rolled or lated tin andother waste compound meta It is also applicable to the extraction of tin mixed or allo ed with any other metal that is not afi'ecte mentioned.

by the solutions hereinbefore a ma m I claim 1. 'llw improvwl IHOCUHS tor the it-novui'y of tin from wastu llllXtlH'trt U1 alloys of or platml goods ot' tin with l':\(l which consists in tt'valing aurh wastv with a solution whivh will (llHHHlVU thv tin without; atl'ovtiug thv load, amt than electrotvning thv resulting liquor.

L 'lhtllJllJlOVWt process to! the recovery of tin t'i'oln tin haul wasttu which consists in treating the lllltttl'liil with a aolutionot stall nit: sulfate having an vxcvas 0t sulfuric :H'ltt lHlXttl with an alkalinu atanuic haloul salt and vlwtl'olyziug tlw l'vsulting liquor.

.3. A process for recovering tin from tin laad waste, which consists in treating the material with a solution of staunin sulfate having an ova-as ot' ault'uriv avitl ltllXtHl with auunoniamt stanniv hitrhlorith amt vh'utrw tying the l'vsulting liquor.

In testimony whui'uot' l haw lltlUHlltO placed my halnh at liflt'ttlzlllX} ram-m this J5 (lay ot Mai'uh HMS. 

